The inventive subject matter relates to power distribution systems and methods and, more particularly, to uninterruptible power supply (UPS) systems and methods.
UPS systems are commonly used in installations such as data centers, medical centers and industrial facilities. UPS systems may be used in such installations to provide backup power to maintain operation in event of failure of the primary utility supply. These UPS systems commonly have an “on-line” configuration including a rectifier and inverter coupled by a DC link that is also coupled to an auxiliary power source, such as a battery, fuel cell or other energy storage device. Other UPS systems may use standby, line-interactive or other architectures.
UPS systems may be implemented using modular assemblies. For example, a UPS system may include multiple UPS modules, each of which may include, for example, a rectifier, an inverter and a DC/DC converter for interfacing to a battery. The UPS modules may be mounted in a common chassis, along with control and interface circuitry, such as bypass switches and the like. The UPS modules may be designed to operate in parallel to provide scalable power capacity, e.g., the modules may be coupled in common to an AC source, a DC source (e.g., a battery) and/or a load. An example of such a modular UPS assembly is the Eaton® Power XPert 9395 UPS (described at http://powerquality.eaton.com), which may be configured to include two or more uninterruptible power modules (UPMs), each of which include a double conversion UPS circuit including a rectifier, inverter and battery converter coupled to a common DC bus. Other modular UPS architectures are described in U.S. patent application Ser. No. 13/936,741 entitled “UPS Systems and Methods Using Variable Configuration Modules,”, filed Jul. 8, 2013 and incorporated herein by reference.